Reactive transport modeling of fluid-rock interactions associated with carbonate diagenesis and implications for reservoir quality prediction

Die Diageneseforschung ist die Grundlage für die Charakterisierung und Exploration von Kohlenwasserstofflagerstätten. Die reaktive Transportmodellierung (RTM) ist ein neuer Ansatz für die Diageneseforschung mit der einzigartigen Fähigkeit zur Quantifizierung und Vorwärtsmodellierung der gekoppelten thermo-hydrochemischen Prozesse der Diagenese. Diese Arbeit untersucht die beiden wichtigsten Fluid-Gesteins-Wechselwirkungen in Karbonatgesteinen, d. h. Dolomitisierung und Verkarstung, basierend auf generischen Modellanalysen und einer Fallstudie im Ordos-Becken, China. Bei der Refluxdolomitisierung werden zunehmender Dolomit, abnehmender Kalzit und dynamische Gipsausfällung/-auflösung beobachtet. Höherer Solesalzgehalt, Temperatur und reaktive Oberfläche tragen zu einem höheren Dolomitisierungsgrad bei. Die Porosität-Permeabilität des Gesteins wird kollektiv durch die Porenzunahme durch Dolomitisierung und die Porenfüllung durch Gipsausfällung gesteuert. Bei der eogenetischen Verkarstung gibt es einen abnehmenden Trend bei der Karbonatauflösung und Gesteinsporosität. Die Dauer der subaerialen Exposition und das Klima bestimmen maßgeblich die vom Karst beeinflusste Tiefe und Porositätszunahme. Die atmosphärische pCO2-Konzentration hat einen geringen Einfluss auf die Karstausdehnung, während sie die Auflösungsgeschwindigkeit beeinflusst. Eine integrierte geologische und RTM-Studie zeigt, dass die Hauptporositäten des Reservoirs der Ordovizium-Majiagou-Formation im Ordos-Becken während der frühen Diagenese entstanden sind. Die mehrstufige Refluxdolomitisierung fand in der eingeschränkten Verdunstungsumgebung statt, was zu einem maximalen Porositätszuwachs von 7,3% des Lagunenfazies-Mikrits führte. Der eogenetische Karst entwickelte sich hauptsächlich in Schwarmfazies-Grainstein mit einer Dauer der subaerialen Exposition von 30–110 ka und einer Porositätszunahme von 1,5–6,7% (durchschnittlich 3,1%). Die weitere Exploration des Reservoirs sollte sich auf die Sedimentumgebung und die Paläogeographie konzentrieren, die die Dolomitisierung und Verkarstung kontrollieren. Die Ergebnisse sind hilfreich, um die räumlich-zeitliche Verteilung und Koevolution von Diagenese und Mineralporosität besser zu verstehen und die Unsicherheit der Vorhersage der Reservoirqualität zu verringern.Diagenesis research is the foundation of hydrocarbon reservoir characterization and exploration. Reactive transport modeling (RTM) is an emerging approach for diagenesis research, with the unique capability of quantification and forward modeling of the coupled thermo-hydro-chemical processes of diagenesis. This thesis investigates the two most important fluid-rock interactions in carbonate rocks, i.e., dolomitization and karstification, based on generic model analyses and a case study in the Ordos Basin, China. For reflux dolomitization, increasing dolomite, decreasing calcite and dynamic gypsum precipitation/dissolution are observed. Higher brine salinity, temperature and reactive surface area contribute to a higher degree of dolomitization. The rock porosity-permeability is collectively controlled by pore-increment via dolomitization and pore-infill by gypsum precipitation. For eogenetic karstification, there is a downward decreasing trend in carbonate dissolution and rock porosity. The duration of subaerial exposure and climate significantly determine the karst-affected depth and porosity increment. The atmospheric pCO2 concentration has a minor impact on the extent of karst, while it affects the dissolution rate. Integrated geological and RTM study shows that the major porosities of the Ordovician Majiagou Formation reservoir in the Ordos Basin were formed during early diagenesis. The multistage reflux dolomitization occurred in the restricted-evaporative environment, giving rise to a maximum 7.3% porosity increment of lagoon-facies micrite. The eogenetic karst developed mainly in shoal-facies grainstone, with the duration of subaerial exposure of 30– 110 ka and porosity increments of 1.5%–6.7% (average 3.1%). Further exploration of the reservoir should focus on sedimentary environment and paleogeography which control dolomitization and karstification. The results are helpful to better understand the spatial-temporal distribution and co-evolution of diagenesis and mineral-porosity, and to reduce the uncertainty of reservoir quality prediction

MicroRNA-124 enhances response to radiotherapy in human epidermal growth factor receptor 2-positive breast cancer cells by targeting signal transducer and activator of transcription 3

Aim To determine whether microRNA (miR)-124 enhances the response to radiotherapy in human epidermal growth factor receptor 2 (HER2)-positive breast cancer cells by targeting signal transducer and activator of transcription 3 (Stat3). Methods miR-29b expression was measured in 80 pairs of breast tumor samples and adjacent normal tissues collected between January 2013 and July 2014. Activity changes of 50 canonical signaling pathways upon miR-124 overexpression were determined using Cignal Signal Transduction Reporter Array. Target gene of miR-124 was determined using Targetscan and validated by Western blotting and dual-luciferase assay. Cell death rate was assessed by propidium iodide (PI)/Annexin V staining followed by flow cytometry analysis. Stat3 and miR-124 expression was further measured in 10 relapsed (non-responder) and 10 recurrence- free HER2-positive breast cancer patients. Results MiR-124 expression was down-regulated in HER2 positive breast cancers compared with normal tissues, and was negatively associated with tumor size. MiR-124 overexpression in HER2 positive breast cancer cell line SKBR3 significantly reduced the activity of Stat3 signaling pathway compared with control transfection (P < 0.001). Bioinformatic prediction and function assay suggested that miR-124 directly targeted Stat3, which is a key regulator of HER2 expression. MiR-124 overexpression down-regulated Stat3 and potently enhanced cell death upon irradiation. Consistently, chemical inhibitor of Stat3 also sensitized HER2-positive breast cancer cells to irradiation. Moreover, increased Stat3 expression and reduced miR-124 expression were associated with a poor response to radiotherapy in HER2-positive breast cancers. Conclusions Weak miR-124 expression might enhance Stat3 expression and radiotherapy resistance in HER2-positive breast cancer cells

MiR-140-5p inhibits morphine tolerance in rats by targeting TLR4

Purpose: To determine the influence of miR-140-5p on morphine tolerance in rats.Methods: Sprague-Dawley (SD) rats were randomly divided into morphine tolerance (MT) and saline control (NS) groups, respectively. Rats in MT group were injected with 10 μL (10 μg) morphine twice daily for seven consecutive days while those in NS group were administered the equivalent volume of normal saline. The maximum effect of morphine (MPE) was computed from tail-flick test results. MiR-140-5p mimics and toll-like receptor 4 (TLR4) lentivirus were transfected separately or co-transfected into model rats. MiR-140-5p and TLR4 expression were determined by quantitative real-time polymerase chain reaction (RT-qPCR) or western blotting. Dual-luciferase reporter assay was used to verify the target relationship between miR-140-5p and TLR4.Results: The expression of miR-140-5p was decreased, while the expression of TLR4 increased in morphine-tolerant rats (p &lt; 0.05). TLR4 was a target of miR-140-5p. At 24 and 48 h after injection, MPE clearly increased and TLR4 expression was reduced under miR-140-5p overexpression or TLR4 knockdown (p &lt; 0.05). Moreover, there were no significant changes in MPE or levels of TLR4 when miR-140-5p and TLR4 were co-transfected into morphine-tolerant rats.Conclusion: MiR-140-5p inhibits morphine resistance in rats via targeted regulation of TLR4 expression. These provide a theoretical basis for the clinical management of morphine tolerance